Evaporative condenser



Aug. 8, 1961 A. E. DEMPSEY, JR 2,995,018

EVAPORATIVE CONDENSER Filed Feb. 17, 1959 Ilo 54 5e FIG. I

HEATED BUILDING AREA 58 I I I I 2 I I 2 FRESH AIR 1 AREA INVENTOR.

ARTHUR E. DEMPSEY, JR. I

ttes

This invention relates to refrigeration of the continuously operatingtype in which a refrigerant is expanded in a refrigeration unit,compressed, and discharged to a condensing coil from which it isreturned to the refrigerating unit; and in particular a refrigeratingsystem in which a refrigerant is compressed and cooled by water notsprayed but dribbled over the lower portion of a condensing coil throughwhich the refrigerant is circulated and over which air is circulated,and in which the volume of cooling water is controlled by a pressureactuated valve connected to the discharge of the compressor, or by asolenoid operated valve.

As the features of the invention are expressable only by manyobjectives, convenient reference to the features of the new combinationwill be found in the following outline:

(1) An annular vertical coil.

(2) A fan pulling air upwardly at the center of the coil.

(3) A block plate preventing air from entering the bottom of the coilwhereby air enters only across and between the coils.

(4) Water dribble loop.

(5) Absence of water recirculation means.

(6) The spacing of the water dribble loop from the top of the coil formaking an air-cooled coil area for pre-cooling refrigerant before itenters a water-cooled lower coil area.

(7) The coil being substantially a single coil substantially open on itsinterior for flow of air without substantial impedance, as distinguishesfrom multiple coils or coils within coils common in the prior art.

The purpose of this invention is to provide a refrigerating system inwhich water dribbled over a condensation coil of the system iscontrolled by the pressure of refrigerant in the system, whereby on cooldays when the ambient temperature, temperature surrounding the coil issufficiently cooled, the system will operate without any water dribblingdown whereby at such time it is cooled only by the surrounding air, withthis air cooling resulting in further water economy, and further inwhich the discharge temperature and pressure of the compressor isgreatly reduced to a percentage depending upon the atmospheric airtemperature whereby the compressor requires less electrical power,resulting in a substantial power saving.

The object of this invention is, therefore, toprovide a condenser havinga water spray loop for dribbling water over a coil wherein the water issupplied from a service water line of a building in which the unit isinstalled and wherein the water supplied to the loop is controlled by apressure actuated valve connected to the discharge side of acompressorof the system.

Heretofore the common type of a system has beenone in which water isdelivered from a line to a storage tank with .the water level controlledby a fioat valve and in.

which. the water is not dribbled but is liberally sprayed over thecondenser coils far in excess of the amount needed for evaporation withthe excess water that falls down over the coils re-circulated by arecirculation pump. With such conventional systems as evaporation occursthe minerals from the water which do not evaporate remain to contaminatethe recirculated water, causing the recirculated water to become what iscommonly called soupy which means saturated with minerals.

As operation of a conventional system continues the atent high mineralcontent causes excessive formation of scale coating on the coils whichreduces the efliciency of heat transfer. An object of my invention istherefore to provide a system which will use a minimum of waterevaporation proportional to cooling attained whereby the quantity ofminerals does not tend to be excessive.

Another object is to provide a system in which water is not recirculatedso that the minerals remaining after evaporation do not re-enter thesystem to contaminate it with excess scale formation.

Still another object is to provide a system of a new combination ofcorrelated inter-cooperating elements in which a small regulated excessamount of water is placed on the coils only slightly in excess of theamount needed for evaporation whereby this slight excess of water tendsto wash away the minerals which would otherwise tend to collect on thecoils through evaporation.

A further disadvantage of conventional recirculated cooling watersystems is in the fact that after the water becomes soupy or of excessconcentration of minerals, it has been the practice to introduce asufiiciently great and wasteful quantity of water from the outsidesupply line into the storage tank for causing water to wastefully spillout near the top of the storage tank through an overflow pipe to cause adilution of the mineral content of the recirculating water in the tank.This spillage causes costly water bills for the users.

It is an object of my system of a new combination of correlatedintercooperating elements to eliminate this waste through making itunnecessary. In prior art systems the water distribution headerdelivering water to the coils has commonly been called a sprayingheader.

I prefer not to call the water distribution header in my system a sprayheader because the word spray brings to mind spray that is wind-blownfrom a sprinkler onto the heads of people and buildings on adjacentproperty. In my system of a new combination of cooperating elements thewater dribbles from the header in a volume proportional to quantity ofcooling attained, so diiferent from the quantity sprayed on in theconventional system.

Also, the word spray, as applied to a conventional system, suggests theuse of a pump and one advantage of my system is to avoid use of a pump,by using water supply line pressure usually a city line pressure.

Elimination of a pump eliminates also first cost maintenance cost andalso operating cost of a pump.

A particular object is to provide a system of a new combination ofcorrelated intercooperating elements in which the first costs of a floatvalve, a circulating pump and an expensive storage tank forrecirculating water are all eliminated and unnecessary.

A further object is to provide for a saving in water usage through thedistribution of water only over a lower portion of a coil with the upperportion of the coil cooled by air as air is quite effective as a coolantin the upper part of the coil because it is the upper part of the coilwhich is so hot, and at a much higher temperature where the percentageof cooling in degrees can be the most effective.

In this way water need be distributed over only the lower part of thecoil as reduces the total water con sumption required.

Still another advantage of air cooling in the upper part of a coil isthat part of the coil is never subjected to scale formation and moreoverthat lower part of the coil which is cooled by water receives a lesserrate of scale deposit because the first coils to receive water coolingare at a lower temperature than would be the case if the water wasdistributed from the top-most part of the coil downwardly and becausewhen a coil is at a lower temperature the rate of scale deposited islower.

A still further object of the invention is to provide a coil for acondenser of a refrigerating system in which the convolutions of thecoil are exposed, thereby facilitating cleaning.

And a still further object is to provide an automatlcall operatingrefrigeration unit in which water is dribbled over a condenser coil ofthe unit providing an evaporative condenser in which the unit is ofsimple and economical construction.

Heretofore water has always been recirculated for use in cooling and iscollected in a catch pan and is re-circulated over and over. Typicaluses of this are found in the patent of T. S. Wetter, titledRefrigerating Apparatus, Patent 2,231,856, issued February ll, 1941, andin the patent to A. W. Ruff, titled Evaporative Refrigerant Condenser,Patent 2,737,789, issued March 13, 1956 In contrast to the standard,conventional system with catch pan and re-circulation, I eliminate thecatch pan for the first time. This elimination of a part or when pipeand pump are considered, rather the elimination of parts, is animportant feature of my invention.

I make possible the elimination of these parts, the elimination of theirexpense and the elimination of their maintenance through the provisionof having my concept of an open, unhoused coil with a water dribbleheader part way down the coil is annular in top plan view, preferablycylindrical, for providing a sufliciency of coil area in a practicalamount of vertical distance, as distinguished from a mere serpentinecoil, thus making it practical to use my new concept of water dribbleinstead of a water spray, making possible for the first time theelimination of catch-pan pump, catch-pan float valve, etc.

Since most spray units also have spray nozzles rather than merelyopenings in spray headers, my system also eliminates these spraynozzles.

In all re-circulating systems as water evaporates minerals are leftbehind whereby as evaporation continues, constant water re-circulationpresent in all systems except the invention herein disclosed, the waterin the catch-pan becomes soupy with minerals, making it a necessarynuisance of maintenance to attend to the matter of adding extra water tothe soupy old Water in order to dilute its high concentration of scaleforming minerals.

In contrast in my system, I simply provide enough excess Waterconstantly to continually carry these minerals away. This is madepossible through using my overall arrangement that makes possible theuse of a minimum amount of water in the first place.

Another nuisance of maintenance with a catch-pan is being sure it isdrained before it freezes in the fall. In many buildings there are nojanitors and the management of the building has many other things ontheir mind and this matter of draining the catch-pan in a unit which isout of their sight, way up on the roof, is a maintenance matter thatthey are often forgetting, resulting in frozen and bursted pipes andbursted catch-pans.

Certain installations of the prior art have multiple coils, one withinthe other as is the regular, orthodox, evaporative condenser which is anest of coils with air passing through them in one direction, and awater spray passing down over them in the other direction. This multiplecoil arrangement blocks air flow.

My coil is designed for fresh air blowing over every square inch.Multiple coils, one within the other, are designed for fresh air flowonly over the lowermost coils. It is heated air from the lower coilsthat contact the middle coil and multiple heated air from the middle andlower coils that hits the upper coils, etc., thus reducing theefiicieney.

A main objective of my invention is the positioning of a water dribbleloop or header about one-fourth or onethird of the way down from the topof the coil. This permits air cooling to remove super-heat from the gasin the upper coils, thus reducing the duty of the Water in condensingthe gas to a liquid in the lower coils.

The economic factor of this greater use of constantly running water issignificant and considerable.

However a main point is that cooling water leaves scale as itevaporates. Cooling air does not. Thus my new concept of cooling firstwith air in the upper coils removes the temperature of the refrigerantconsiderably to the end that by the time the refrigerant has reached thelower two-thirds of the coils which are being cooled by water, therefrigerant is already at a temperature sufiiciently low to greatlyreduce the amount of scale formation.

It must be remembered that water forms scale at a much higher rate whenit strikes the pipe full of very hot refrigerant than it does when itstrikes a coil with cool refrigerant, thus cooling the refrigerant firstby air delivers the refrigerant in a cooler state to the lower coilswhere the water cooling forms scale at a substantially lesser rate thanwould be formed if there would be no air cooling in the area above mywater-cooled lower coils.

With these and other objects and advantages in view the inventionembodies a vertically disposed coil having a spray loop or header spaceddownwardly from the upper end and having a motor driven fan positionedon the upper end for drawing air upwardly through the coil, and apressure actuated valve positioned in a connection from the water headerto a service water line to regulate the quantity of water supplied tothe water header, and connected to the discharge side of a compressor ofthe refrigeration unit, whereby the water dribble is controlled by thepressure of the discharge of the compressor.

Other features and advantages of the invention will appear from thefollowing description taken in connection with the drawings, wherein:

FIGURE 1 is a diagrammatic view showing the improved refrigeration unitwith the coil of the condenser supported in spaced relation to a floor,and with a water dribble header in the coil connected to a service lineand provided with a pressure actuated valve connected in the dischargeof a compressor of the unit.

FIGURE 2 is a plan view taken on line 2-2 of FIG- URE 1 showing a waterdribbling loop or header positioned in the coil of the condenser.

FIGURE 3 is a cross section through one of the convolutions of thecondenser coil taken on line 3-3 of FIGURE 2 showing the water dribbleheader secured to the coil, such as by welding.

FIGURE 4 is a modification showing a solenoid actuated valve instead ofthe pressure actuated valve for controlling the water supplied to thewater dribble header.

While one embodiment of the invention is illustrated in the abovereferred to drawings, it is to be understood that they are merely forthe purpose of illustration, and that various changes in constructionmay be resorted to in the course of manufacture in order that theinvention may be utilized to the best advantage according tocircumstances which may arise, without in any manner departing from thespirit and intention of the device, which is to be limited only inaccordance with the appended claims. And while there is stated theprimary field of utility of the invention, it remains obvious that itmay be employed in any other capacity wherein it may be foundapplicable.

In the accompanying drawings, and in the following specification, thesame reference characters are used to designate the same parts andelements throughout, and in which the numeral 10 refers to the inventionin its entirety, numeral 12 indicating a vertically disposed condensercoil, numeral 14 a water dribble loop or header spaced downwardly fromthe upper end of the coil, numeral 16 a fan rotated by a motor 18mounted by arms 20 on a head 22, numeral 24 a pressure actuated valveassembly positioned in a tube 26 connecting the water dribble header 14to a service pipe 28 and conof the coil 12 to a compressor 32. in arefrigeration unit including a coil 34, and numeral 36 a manuallyactuated valve also positioned in the tube 26.

A dotted line 37 has been drawn through FIG. 1 to indicate the insideand outside of a building which is significant for the followingreasons: whereas in systems which use storage tanks, there is thenecessity of draining the storage tank in the winter to avoid damagefrom freezmg.

It is my desire to place all parts of the system shown on the righthandside of the dotted line 37 in FIG. 1 on the inside of a building wherebuilding heat is such that liquid in these parts is in no danger offreezing.

The water line 26 is preferably made of pipe that is heavy enough so asto avoid splitting of the pipe 26 by freezing of the water thereinwhereby in this way I provide a system that is safe in sub-zerotemperatures and which eliminates the necessity of drainage of the watertank as was necessary in prior art systems which used water tanks. Sincethe coil is cooled by air and not by water when the atmospherictemperature is below freezing there are no disadvantages.

The condenser coil 12 is provided with vertically disposed bars 38having legs with upper sections 40 and lower sections 42 having flanges44 on lower ends extended from the lower ends, and the upper ends of thebars are secured in the head 22, being secured to the inner surface of aflange 46 depending from the head. The head 22 is provided with anopening 48 below which the fan 16 is positioned. The fan is carried onthe lower end of the motor shaft 50', and the arms 20 which support themotor are secured to the upper surface of the head by flanges 52. Themotor is provided with an electric cord 54 having a conventional plug 56on the extended end.

The pipe connecting the upper end of the coil 12 to the compressor 32,which is indicated by the numeral 58, is provided with a fitting 60 towhich the tube 30 is connected. The tube 26 is provided with a coupling62. by which the tube is connected to the water dribble header 14, andthe water dribble header is perforated 55 to pro vide a dribble, asshown in FIGURE 4. The dribble header is secured to one of theconvolutions of the coil 12 by welding, as indicated by the numeral 64,or by other means.

In the modification illustrated in FIGURE 4 the pressure actuated valve24 is replaced by a solenoid valve 66 connected to a pressure switch 68-in a pipe 70 similar to the pipe 58 by a wire 72, the opposite terminalof the valve 66 being connected by a wire 74 to a source of currentsupply, and the opposite terminal of the switch 68 being connected by awire 76 to the opposite terminal of the source of current supply. Thevalve 66 is positioned in a tube 78 similar to the tube 26, and the tube78 is connected to a dribble header 80 similar to the water dribbleheader 14.

A circular horizontally disposed plate 82 is secured to the uprights 38and adjacent the lowermost one of the convolutions of the coil 12.

Operation The refrigeration unit is installed as illustrated anddescribed and refrigerant or a suitable coolant is compressed by thecompressor 32 and circulated through the condenser coil 12 with thepressure in pipe 58 actuating the pressure valve assembly 24 to permitwater to pass to the water dribble header 14 proportional to pressure inpipe 58 whereby water is admitted to the dribble loop by said valveassembly proportional to pressure in said piping so that more water isadmitted to said dribble loop when pressure in pipe 58 is higher andless is admitted when such pressure is lower for effective andeconomical water conservation. It is preferred that the water dribbleheader be spaced downwardly in the coil a distance corresponding toapproximately one-third of the length of the coil.

The flow of water may also be, controlled'by electricalf means with thepressure actuated switch 68. closing a circuit to the solonoid actuatedvalve 66, and in such a case the switch 68 and valve 66, electricalenergy and wiring all together compose a pressure valve assembly in themeaning of the appended claims.

It will be seen that when the fan 16 is in operation, air will be drawnthrough the coils to expedite evapora tion of water on the coil 12.Since the plate 82 blocks the lower end of the coil 12, air is drawn infrom the sides of the coil whereby each convolution is subjected to adraft of air extending completely around it and not just verticallythrough the center of the coil as would be if the plate 82 was not used.I prefer that the amount of line pressure flow actually used by mysystem by regulated by the valve 36 so as to be slightly more thanneeded to replace water which evaporates from the coil whereby use of afloat valve controlled water level in a storage tank is unnecessaryeliminating the float valve, the pump, and the storage tank, madepractical actually by the characteristic low water-use efliciency of mysystem.

This inherent characteristic attained by my concept is a new combinationof features, never heretofore combined, one feature of which is a coilof a particular shape and position in my water distribution arrangement.

From the foregoing specification, it will become apparent that theinvention disclosed will adequately accomplish the functions for whichit has been designed and in an economical manner, and that itssimplicity, accuracy, and ease of operation are such as to provide arelatively inexpensive device, considering what it will accomplish, andthat it will find an important place in the art to which it appertainswhen once placed on the market.

It is thought that persons skilled in the art to which the inventionrelates will be able to obtain a clear understanding of the inventionafter considering the description in connection with the drawings.Therefore, a more lengthy description is regarded as unnecessary.

Changes in shape, size and arangement of details and parts such as comewithin the purview of the invention claimed may be resorted to in actualpractice, if desired.

Having now described the invention that which is claimed to be new anddesired to be procured by Letters Patent is:

1. A refrigerating condenser comprising a vertically disposed condensercoil of annular shape in top plan view having an opening therethroughfrom bottom to top, said coil being substantially a single coilsubstantially open on its interior for flow of air therethrough withoutsubstantial impedance, means for supporting the coil upright, blockingmeans extending across the bottom of said opening in said coil andblocking air flow into the coil bottom except between the convolutions,means at top of said coil and positioned to draw air inwardly throughthe convolutions of the coil and upwardly through the coil, means for somounting said air drawing means, and a horizontally positioned annularwater dribble loop, of substantially the same shape as that of the coil,mounted in the coil and spaced downwardly from the upper end thereof asubstantial number of convolutions, whereby the refrigerant flows fromthe top downwardly and is first cooled with air in the upper part of thecoil above the loop whereby its temperature is reduced before it reachesthe water cooled lower part of the coil below said loop so that watercooling under said loop in the lower part of the coil will not producescale formation at such a high rate as it would without firstair-cooling the refrigerant in the upper part of the coil which is abovesaid loop, and said loop being spaced a substantial distance above thebottom of the coil whereby the lower Watercooled portion of the coil isof substantial size for effective water cooling, said condenser coilbeing substantially open at its sides whereby external air from theareas at the sides of said coil can enter between and sweep over saidconvolutions in a first and cooling stage of air motion,

r i v s'aidexternal air being of lower humidity and much lowertemperature than relatively saturated air passing upwardly from theinterior of the lower part of the coil, andwhereby said air from thesides of said coil, when it has passed across said convolutions andaccomplished its heat transfer and effectively caused water evaporationthereby, is exhausted upwardly in a second and discharge stage .of airmotion through the interior of said coil and out the top of said coil, acompressor, piping operably connecting said coil and said compressor,and means for delivering water to said water dribble loop.

2. The combination of claim 1 in which said means for delivering waterto said water dribble loop comprises a pressure responsive valveassembly having an inlet connectable to a water line and having anoutlet, means connecting said pressure valve assembly outlet to saidWater dribble loop, and means operably connecting the pres- 8 q sureresponsive valve assembly to said piping where by water is admitted tosaid dribble loop by. said valve assembly in proportion to pressure insaid piping so that more water is admitted to said dribble looplwhe'upressure in said piping is higher and less water is admitted when saidpressure is lower for effective and eco nomical conservation of coolingwater.

References Cited in the file of this patent UNITED STATES PATENTS ufi iMar. 13, 1956

